Acousto-optic element, acousto-optic element array, and display apparatus including the acousto-optic element

ABSTRACT

Provided are an acousto-optic element, an acousto-optic element array, and a display apparatus including the acousto-optic element array. The acousto-optic element includes: an acousto-optic modulator which includes an acousto-optic layer formed of an acousto-optic material; a light supplier which supplies light to the acousto-optic modulator in a first direction; a first sound-wave modulator which applies first elastic waves to the acousto-optic modulator in a second direction; and a second sound-wave modulator which applies second elastic waves to the acousto-optic modulator in a third direction. The light supplied from the light supplier to the acousto-optic modulator is deflected by diffraction caused by the first elastic waves applied from the first sound-wave modulator and diffraction caused by the second elastic waves applied from the second sound-wave modulator, and is output from the acousto-optic modulator through a front side of the acousto-optic modulator.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Divisional of U.S. application Ser. No. 14/321,353, filed onJul. 1, 2014, and claims priority from Korean Patent Application No.10-2013-0152652, filed on Dec. 9, 2013, in the Korean IntellectualProperty Office, the disclosures of which are incorporated herein byreference in their entireties.

BACKGROUND 1. Field

The exemplary embodiments relates to an acousto-optic element, anacousto-optic element array, and a display apparatus including theacousto-optic element. In particular, exemplary embodiments relate to anacousto-optic element capable of directing light in multiple directions,an acousto-optic element array, and a display apparatus including theacousto-optic element.

2. Description of the Related Art

An acousto-optic effect refers to the effect of changing opticalcharacteristics of media using sound waves or ultrasonic waves. If lightis incident on a medium changed in optical characteristics by theacousto-optic effect, the light is modulated according to the amount ofchange in the optical characteristics of the medium and is output fromthe medium. For example, the refractive index of a medium may beperiodically changed by the acousto-optic effect so as to use the mediumas a phase grating capable of diffracting light. In this case, theintensity or diffraction angle of light may be adjusted by changing theintensity or frequency of sound waves or ultrasonic waves applied to themedium. Thus, an optical modulator for modulating the amplitude of lightor a scanner for deflecting light may be realized using theacousto-optic effect.

Research has been conducted on display technology using such opticalmodulators or scanners using the acousto-optic effect.

Related art binocular-parallax 3-dimensional image displays provide3-dimensional images to viewers by generating left-eye and right-eyeimages having different viewpoints. Such 3-dimensional image displaysmay be classified into a glasses type and a non-glasses type.

Research into holographic 3-dimensional image displays has beenconducted to provide more natural 3-dimensional images. Light may beconsidered as waves having intensity and phase, and holography is usedto display 3-dimensional images by controlling the intensity and phaseof light. Therefore, holographic 3-dimensional image displays includeelements capable of controlling the amplitude (intensity) or phase oflight.

SUMMARY

Exemplary embodiments may provide an acousto-optic element capable ofdirecting light in multiple directions.

Exemplary embodiments may provide a flat panel type acousto-opticelement array capable of directing light in multiple directions.

Exemplary embodiments may provide a display apparatus including theacousto-optic element array.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to an aspect of the exemplary embodiments, an acousto-opticelement includes: an acousto-optic modulator which includes anacousto-optic layer formed of an acousto-optic material; a lightsupplier which supplies light to the acousto-optic modulator in a firstdirection; a first sound-wave modulator which applies first elasticwaves to the acousto-optic modulator in a second direction; and a secondsound-wave modulator which applies second elastic waves to theacousto-optic modulator in a third direction, wherein the light suppliedfrom the light supplier to the acousto-optic modulator is deflected bydiffraction caused by the first elastic waves applied from the firstsound-wave modulator and diffraction caused by the second elastic wavesapplied from the second sound-wave modulator, and is output from theacousto-optic modulator through a front side of the acousto-opticmodulator.

The first to third directions may be different directions defined in theacousto-optic layer.

The acousto-optic material may include at least one of ZnO, LiNbO₃,LiTaO₃, quartz, TiO₂, Si, SiN, AlN, SiO₂, and SrTiO₃.

The acousto-optic modulator may include: a core layer which receiveslight; a first cladding layer disposed under the core layer and having arefractive index which is different from a refractive index of the corelayer; and a second cladding layer disposed above the core layer andhaving a refractive index which is different from the refractive indexof the core layer.

The refractive index of the core layer may be greater than therefractive index of each of the first cladding layer and the secondcladding layer.

At least one of the first cladding layer and the second cladding layermay be an air layer.

The acousto-optic layer may be at least one of the core layer, the firstcladding layer, and the second cladding layer.

The core layer may include a periodic photonic crystal structure inwhich a plurality of unit cells including a pattern are repeated.

The periodic photonic crystal structure of the core layer may be aperiodic structure in which at least two materials having differentdielectric constants are periodically arranged in a 2-dimensional or3-dimensional manner.

The first cladding layer and the second cladding layer may include asame periodic photonic crystal structure as the periodic photoniccrystal structure of the core layer.

The periodic photonic crystal structure of the core layer may be formedin such a manner that an equifrequency contour of a plurality of opticalwave vectors may be flat in the first direction and the seconddirection.

The photonic crystal structure of the acousto-optic modulator maydecelerate light or surface acoustic waves.

The photonic crystal structure may have periodic sizes of severalnanometers to several hundreds of nanometers.

The core layer may include a dielectric substrate and a plurality ofholes formed in the dielectric substrate, and the holes may be arrangedin a periodic structure in which unit cells having a predeterminedpattern are repeated.

Air may be filled in the holes, or a dielectric material having arefractive index different from that of the dielectric substrate may befilled in the holes.

The core layer may include a dielectric substrate and a plurality ofdielectric pillars formed in the dielectric substrate, and thedielectric pillars may be arranged in a periodic structure in which unitcells having a predetermined pattern are repeated.

The acousto-optic modulator may further include a reflection layer underthe first cladding layer.

The acousto-optic modulator may further include a substrate under thereflection layer.

The acousto-optic layer may be at least one of the core layer, the firstcladding layer, the second cladding layer, the reflection layer, and thesubstrate.

At least one of the core layer, the first cladding layer, the secondcladding layer, the reflection layer, and the substrate may be formed ofa piezoelectric material which is used as a sound wave generator of atleast one of the first sound-wave modulator and the second sound-wavemodulator. The piezoelectric material comprises at least one of ZnO,PZT, LiNbO₃, LiTaO₃, quartz, and SrTiO₃.

A first sound wave generator of the first sound-wave modulator and asecond sound wave generator of the second sound-wave modulator may beformed in different layers.

At least two of the core layer, the first cladding layer, the secondcladding layer, the reflection layer, and the substrate may be formed ofa piezoelectric material to be used as the first and second sound wavegenerators.

The light supplier may include: an optical waveguide disposed at a firstside of the acousto-optic modulator; and an optical coupler disposedbetween the optical waveguide and the acousto-optic modulator.

The optical coupler may be a grating coupler. The grating coupler may bea pattern of grooves or materials having different refractive indexes.

The acousto-optic modulator may have at least three sides, and the lightsupplier, the first sound-wave modulator, and the second sound-wavemodulator may be disposed at different sides of the acousto-opticmodulator.

The light supplier may be disposed at a first side of the acousto-opticmodulator, the first sound-wave modulator may be disposed at a secondside of the acousto-optic modulator, and the second sound-wave modulatormay be disposed at a third side of the acousto-optic modulator, whereinthe first to third sides may be different sides.

The first sound-wave modulator may include: a first sound wave generatordisposed at the second side of the acousto-optic modulator; and a firsthigh-frequency waveguide through which first high-frequency power mayapplied to the first sound wave generator, wherein the second sound-wavemodulator may include: a second sound wave generator disposed at thethird side of the acousto-optic modulator; and a second high-frequencywaveguide through which second high-frequency power may be applied tothe second sound wave generator.

The first sound wave generator and the second sound wave generator maybe formed in different layers.

The first high-frequency waveguide and the second high-frequencywaveguide may be formed in different layers.

The first high-frequency power of the first high-frequency waveguide,and the second high-frequency power of the second high-frequencywaveguide may be respectively adjusted in frequency and phase andintensity according to the frequency, such that a shape, direction, andintensity of the light output is controlled from the acousto-opticmodulator through the front side of the acousto-optic modulator.

A plurality of sound absorbing members may be disposed outside the firstsound-wave modulator and the second sound-wave modulator, respectively.

According to another aspect of the exemplary embodiments, anacousto-optic element array includes a plurality of acousto-opticelements, wherein each of the plurality of acousto-optic elementsincludes: an acousto-optic modulator which includes an acousto-opticlayer formed of an acousto-optic material; a light supplier whichsupplies light to the acousto-optic modulator in a first direction; afirst sound-wave modulator which applies first elastic waves to theacousto-optic modulator in a second direction; and a second sound-wavemodulator which applies second elastic waves to the acousto-opticmodulator in a third direction, wherein the light supplied from thelight supplier to the acousto-optic modulator is deflected bydiffraction caused by the first elastic waves applied from the firstsound-wave modulator and diffraction caused by the second elastic wavesapplied from the second sound-wave modulator, and is output from theacousto-optic modulator through a front side of the acousto-opticmodulator, wherein a plurality of acousto-optic modulators correspondingto each of the plurality of acousto-optic elements are arranged in atleast one line.

The acousto-optic modulator may be arranged in a single line.

The light supplier, the first sound-wave modulator, and the secondsound-wave modulator of each of the plurality of acousto-optic elementsmay be disposed at different positions of a front end, a rear end, aside, and an other side of the single line of the acousto-opticmodulators.

One of the light supplier, the first sound-wave modulator, and thesecond sound-wave modulator which is disposed at the side or the otherside of the single line of the acousto-optic modulators may be formed toextend along the single line and may be commonly used for theacousto-optic modulators.

One of the light supplier, the first sound-wave modulator, and thesecond sound-wave modulator which is disposed at the side or the otherside of the line of the acousto-optic modulators may be individuallyprovided for each of the acousto-optic modulators.

One of the light supplier, the first sound-wave modulator, and thesecond sound-wave modulator which is disposed at the front end or therear end of the line of the acousto-optic modulators may be commonlyused for the acousto-optic modulators.

The acousto-optic modulators may be arranged in a plurality of columnsand a plurality of rows.

The light supplier of the plurality of acousto-optic elements may extendalong an outer side of one of outermost columns of the acousto-opticmodulators.

The light supplier of the plurality of acousto-optic elements may extendalong sides of the respective columns of the acousto-optic modulator.

The first sound-wave modulator of the plurality of acousto-opticelements may extend along an outer side of one of outermost rows of theacousto-optic modulators.

A plurality of the first sound-wave modulators of the plurality ofacousto-optic elements may be arranged along an outer side of one ofoutermost rows of the acousto-optic modulators, so as to be respectivelydisposed at the columns of the acousto-optic modulators.

A plurality of first sound-wave modulators of the plurality ofacousto-optic elements may be formed to extend along sides of therespective rows of the acousto-optic modulators.

A plurality of first sound-wave modulators of the plurality ofacousto-optic elements may be individually arranged at sides of therespective rows of the acousto-optic modulators.

The second sound-wave modulator of the plurality of acousto-opticelements may extend along an outer side of the other of the outermostcolumns of the acousto-optic modulators.

A plurality of second sound-wave modulators of the plurality ofacousto-optic elements may be arranged along the outer side of an otherof the outermost columns of the acousto-optic modulators, so as to berespectively disposed at the rows of the acousto-optic modulators.

A plurality of second sound-wave modulators of the plurality ofacousto-optic elements may be formed to extend along sides of therespective columns of the acousto-optic modulators.

A plurality of second sound-wave modulators of the plurality ofacousto-optic elements may be individually arranged at sides of therespective columns of the acousto-optic modulators.

According to another aspect of the exemplary embodiments, a displayapparatus includes a display panel including the acousto-optic elementarray, wherein a plurality of images are displayed by controlling atleast one of directions, phases, and intensities of the light outputfrom front sides of the acousto-optic modulators 2-dimensionallyarranged in the display panel.

The display apparatus displays 2-dimensional images having a singleviewpoint regardless of the directions of the light output from thedisplay panel.

The display panel may adjust viewpoint data of the images according tothe directions of the light output from the display panel so as to format least two visual fields for displaying 3-dimensional images.

Switching between 2-dimensional images and 3-dimensional images may beperformed by selectively adjusting image data according to thedirections of the light output from the display panel.

The at least two visual fields may be formed in at least one of ahorizontal direction and a vertical direction.

A plurality of hologram images may be displayed by adjusting theintensities and the phases of the light output from the display panelaccording to the directions of the light.

According to exemplary embodiments, the direction of the light outputfrom the acousto-optic element may be controlled in horizontal andvertical directions by using the acousto-optic effect, and the shape,intensity, and/or phase of the light may also be controlled.

According to exemplary embodiments, the acousto-optic element array maybe flat and may be used in a 2-dimensional display apparatus,3-dimensional display apparatus, a 2D/3D convertible display apparatus,a multi-viewpoint 3-dimensional display apparatus, and a holographicdisplay apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a schematic plan view illustrating an acousto-optic elementaccording to according to an embodiment;

FIG. 2 is a schematic side sectional view of the acousto-optic element,taken along line I-I′ of FIG. 1;

FIG. 3 is a schematic perspective view illustrating an exemplaryphotonic crystal structure of a core layer of the acousto-optic elementof FIG. 1;

FIG. 4 is a view for explaining an operation of the acousto-opticelement of FIG. 1;

FIG. 5 is a view illustrating light propagation directions in theacousto-optic element of FIG. 1 by using a wavenumber space;

FIG. 6 is a real-space view illustrating propagation directions of thelight output from the acousto-optic element of FIG. 1;

FIG. 7 is a schematic plan view illustrating an acousto-optic elementarray according to according to an embodiment;

FIG. 8 is a view illustrating an exemplary arrangement of a light supplyunit and first and second sound wave generators in the acousto-opticelement array of FIG. 7;

FIGS. 9A to 9H are views illustrating exemplary arrangements of lightsupply units and first and second sound-wave modulation units inacousto-optic element arrays according to embodiments;

FIGS. 10A to 10C are views illustrating exemplary arrangements of lightsupply units and first and second sound-wave modulation units inacousto-optic element arrays according to other embodiments; and

FIG. 11 is a schematic view illustrating a 2D/3D convertible3-dimensional display apparatus including an acousto-optic element arrayaccording to an embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings. In this regard, thepresent embodiments may have different forms and should not be construedas being limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects of the present description. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items. Expressions such as “at least one of,” whenpreceding a list of elements, modify the entire list of elements and donot modify the individual elements of the list.

Hereinafter, exemplary embodiments will be described in detail withreference to the accompanying drawings. In the drawings, like referencenumbers refer to like elements, and the size of each element may beexaggerated for clarity of illustration.

FIG. 1 is a schematic plan view illustrating an acousto-optic element100 according to according to an embodiment, and FIG. 2 is a schematicside sectional view of the acousto-optic element 100, taken along lineI-I′ of FIG. 1.

Referring to FIGS. 1 and 2, the acousto-optic element 100 of theembodiment may include an acousto-optic modulation unit 110 provided ona substrate 117, a light supply unit 130 configured to supply light tothe acousto-optic modulation unit 110, a first sound-wave modulationunit 150 configured to apply first elastic waves A_(H) to theacousto-optic modulation unit 110, and a second sound-wave modulationunit 170 configured to apply second elastic waves A_(V) to theacousto-optic modulation unit 110.

The acousto-optic modulation unit 110 may include a core layer 111, afirst cladding layer 112 disposed on a lower surface of the core layer111, and a second cladding layer 113 disposed on an upper surface of thecore layer 111. The core layer 111 may have a refractive index greaterthan those of the first and second cladding layers 112 and 113. At leastone of the first and second cladding layers 112 and 113 may be an air orvacuum layer. In this case, at least one of the first and secondcladding layers 112 and 113 may be omitted.

A reflection layer 115 may be further provided on a lower side of thefirst cladding layer 112. The reflection layer 115 may be formed of ametal such as aluminum (Al) or silver (Ag). When light is incident onthe acousto-optic modulation unit 110 and exit from the acousto-opticmodulation unit 110 after being modulated, downwardly propagating lightmay be reflected to an upper side by the reflection layer 115.

At least one of the core layer 111, the first cladding layer 112, andthe second cladding layer 113 may be formed of an acousto-optic materialhaving the acousto-optic effect. In this case, if sound waves areapplied to the acousto-optic modulation unit 110, the density of theacousto-optic modulation unit 110 may be locally varied in a periodicmanner according to the compression and rarefaction of the sound waves.Examples of the acousto-optic material include ZnO, LiNbO₃, LiTaO₃,quartz, TiO₂, Si, SiN, AlN, SiO₂, and SrTiO₃.

The acousto-optic modulation unit 110 has at least three sides (first tothird sides 110 a, 110 b, and 110 c). For example, as shown in FIG. 1,the acousto-optic modulation unit 110 may have four sides (that is, arectangular shape when viewed from the topside).

The light supply unit 130 is disposed at the first side 110 a of theacousto-optic modulation unit 110 to supply light L in a firstdirection. The light supply unit 130 may include an optical coupler 135.

An optical waveguide 131 may extend along the first side 110 a of theacousto-optic modulation unit 110 to transmit light emitted from a lightsource (not shown), and the optical coupler 135 may be disposed at thefirst side 110 a of the acousto-optic modulation unit 110 to couplelight transmitted through the optical waveguide 131 to the core layer111 of the acousto-optic modulation unit 110. For example, as shown inFIG. 2, the second cladding layer 113 may have a stepped portion on thefirst side 110 a of the acousto-optic modulation unit 110 to partiallyexpose the core layer 111. The optical waveguide 131 may be disposedbetween a stepped side surface 113 a of the second cladding layer 113and an exposed top surface region of the core layer 111 so that theoptical waveguide 131 may make contact with the top surface of the corelayer 111 of the acousto-optic modulation unit 110. The optical coupler135 may be a grating coupler formed in the optical waveguide 131disposed on the exposed top surface region of the core layer 111. Forexample, the grating coupler may be a grating pattern formed in theoptical waveguide 131 by using materials having different refractiveindexes. In another example, the grating coupler may be a groove gratingpattern formed between the optical waveguide 131 and the core layer 111.In FIG. 1, the incident direction of light L is a positive (+) V-axisdirection. However, the incident direction of light L is not limitedthereto. According to the coupling method of the optical coupler 135, afirst direction may be an oblique direction from the light supply unit130 to the first side 110 a of the acousto-optic modulation unit 110.

The first sound-wave modulation unit 150 may include a first sound-wavegenerator 151 disposed at the second side 110 b of the acousto-opticmodulation unit 110 to generate first elastic waves A_(H) in a seconddirection and a first high-frequency waveguide 155 to apply firsthigh-frequency power to the first sound-wave generator 151. Similarly,the second sound-wave modulation unit 170 may include a secondsound-wave generator 171 disposed at the third side 110 c of theacousto-optic modulation unit 110 to generate second elastic waves A_(V)in a third direction and a second high-frequency waveguide 175 to applysecond high-frequency power to the second sound-wave generator 171. Thefirst and second directions are different from the first direction inwhich light is incident. For example, as shown in FIG. 1, the seconddirection may be a negative (−) H-axis direction, and the thirddirection may be a negative (−) V-axis direction. The first and secondsound-wave modulation units 150 and 170 may include an earth wire orcommon wire for the first and second sound-wave generators 151 and 171.

For example, the first and second sound-wave generators 151 and 171 maybe electro-acoustic modulators capable of generating surface acousticwaves (SAWs) or bulk acoustic waves (BAWs). The first and secondsound-wave generators 151 and 171 may be disposed in one or more of thecore layer 111, the first cladding layer 112, the second cladding layer113, the reflection layer 115, and the substrate 117 or may be disposedtherebetween. In addition, the first and second high-frequencywaveguides 155 and 175 may be provided in different layers so that thefirst and second high-frequency waveguides 155 and 175 may be arrangedin a crossing manner in an array (described later) of such acousto-opticelements 100.

A first sound absorbing member 159 is disposed outside the firstsound-wave generator 151, and a second sound absorbing member 179 isdisposed outside the second sound-wave generator 171. The first andsecond sound absorbing members 159 and 179 are used to prevent first andsecond elastic waves A_(H) and A_(V) generated by the first and secondsound-wave generators 151 and 171 from propagating outward. Therefore,when an array is formed of such acousto-optic elements 100 of thecurrent embodiment, interference between neighboring acousto-opticelements 100 may be prevented. In a related art, natural acousto-opticmaterials have limited acousto-optic conversion efficiency. In contrast,in the current embodiment, the acousto-optic element 100 may have aphotonic crystal structure for obtaining a wider diffraction angle rangeby the acousto-optic effect. In the current embodiment, the core layer111 may have a 2-dimensional or 3-dimensional periodic photonic crystalstructure. Photonic crystals may be defined as a periodic structure inwhich at least two materials having different dielectric constants (orrefractive indexes) are periodically arranged. For example, photoniccrystals may be a periodic structure having a submicron size period,that is, a size period of several nanometers to several hundreds ofnanometers (for example, a size period equal to or less thanwavelengths). Such photonic crystals may transmit, reflect, or absorbalmost 100% of light having a particular wavelength band. A lightwavelength band not passing through photonic crystals is known as aphotonic bandgap. Photonic crystals having such a photonic bandgap areused in various fields.

FIG. 3 is a schematic perspective view illustrating an exemplaryphotonic crystal structure of the core layer 111 of the acousto-opticmodulation unit 110 according to the embodiment. Referring to FIG. 3,the core layer 111 may include a dielectric substrate 111 a and aplurality of holes 111 b vertically formed in the dielectric substrate111 a. For example, if the core layer 111 is formed of an acousto-opticmaterial, the dielectric substrate 111 a may be the acousto-opticmaterial. In the example shown in FIG. 3, the plurality of holes 111 bvertically penetrate the dielectric substrate 111 a. However, theplurality of holes 111 b may not penetrate the dielectric substrate 111a. Air may be simply filled in the holes 111 b, or a dielectric materialhaving a refractive index different from that of the dielectricsubstrate 111 a may be filled in the holes 111 b. In addition, the holes111 b may be arranged in a periodic structure in which unit cells havingrectangular patterns are repeated. In the example shown in FIG. 3, theholes 111 b have a circular cylinder shape. However, the holes 111 b mayhave a rectangular cylinder shape or any other polygonal cylinder shape.

In the photonic crystal structure shown in FIG. 3, a repetitive patternmay be directional. Thus, refractive index distribution by the photoniccrystal structure may be anisotropic. Because of such anisotropicrefractive index distribution, an equifrequency contour 207 (refer toFIG. 5) of optical wave vectors in a photonic crystal region of theacousto-optic modulation unit 110 may be flat in the first and seconddirections.

The photonic crystal structure of the core layer 111 shown in FIG. 3 isan example. That is, the photonic crystal structure of the core layer111 may be variously designed. Various periodic structures other thanthe periodic structure shown in FIG. 3 may be used. For example, insteadof the vertical holes 111 b, hexahedral or spherical dielectric partsmay be periodically arranged in the dielectric substrate 111 a. Althoughthe photonic crystal structure shown in FIG. 3 is 2-dimensional, thecore layer 111 may have a 3-dimensional photonic crystal structure (thatis, a photonic crystal structure having periodicity in the length,width, and height directions thereof). As described above, the photoniccrystal structure of the core layer 111 may be variously designedaccording to a required equifrequency contour of optical wave vectors.

In addition, the first and second cladding layers 112 and 113 may havethe same photonic crystal structure as that of the core layer 111. Insome embodiments, however, only the core layer 111 may have a photoniccrystal structure, and the first and second cladding layers 112 and 113may not have a photonic crystal structure.

FIG. 4 is a view for explaining an operation of the acousto-opticelement 100 according to the embodiment, FIG. 5 is a view illustratinglight propagation directions in the acousto-optic element 100 by using awavenumber space, and FIG. 6 is a real-space view illustratingpropagation directions of light output from the acousto-optic element100.

Referring to FIG. 4, light L propagates through the optical waveguide131 of the light supply unit 130 and enters the acousto-optic modulationunit 110 through the optical coupler 135 (refer to FIGS. 1 and 2). Thelight L is incident on the acousto-optic modulation unit 110 in a firstdirection (for example, a positive (+) V-axis direction or a directionmaking an acute angle therewith) and is diffracted and deflected by theacousto-optic effect caused by first elastic waves A_(H) generated in asecond direction (for example, a negative (−) H-axis direction) by thefirst sound-wave modulation unit 150 and second elastic waves A_(V)generated in a third direction (for example, a negative (−) V-axisdirection) by the second sound-wave modulation unit 170. Then, the lightL exits from the acousto-optic modulation unit 110.

Deflection of light L by the acousto-optic effect of first and secondelastic waves A_(H) and A_(V) may be understood more clearly byreferring to the wavenumber space shown in FIG. 5.

Referring to FIG. 5, light L in the optical waveguide 131 has a wavevector k_(H). Reference numeral 201 denotes an equifrequency contour ofwave vectors that the light L may have in the optical waveguide 131, andreference numeral 211 denotes the tip of the wave vector k_(H) of thelight L in the optical waveguide 131. The light L is incident on theacousto-optic modulation unit 110 from the optical waveguide 131 by theoptical coupler 135. This may be understood that the wave vector k_(H)of the light L in the optical waveguide 131 is changed in direction by awave vector k_(coupler) resulting from the optical coupler 135. That is,when the origin of the wave vector k_(H) of the light L is on the originof the wavenumber space, the tip of the wave vector k_(H) is changedfrom a point 211 to a point 212 by the optical coupler 135. Referencenumeral 203 denotes an equifrequency contour of wave vectors that thelight L may have in the first and second cladding layers 112 and 113.Since the core layer 111 has a refractive index greater than those ofthe first and second cladding layers 112 and 113, an equifrequencycontour of wave vectors that the light L may have in the core layer 111may be outside of the equifrequency contour 203 in the first and secondcladding layers 112 and 113.

Since the acousto-optic modulation unit 110 has the photonic crystalstructure, the equifrequency contour 207 of wave vectors that the lightL may have in the photonic crystal structure may be flat in the firstand second directions. In this way, since wave vectors that the light Lmay have in the photonic crystal structure of the acousto-opticmodulation unit 110 are limited, the tip of the wave vector of the lightL is changed from the point 212 to a point 213 in the acousto-opticmodulation unit 110 by first elastic waves A_(H). In addition, the tipof the wave vector of the light L is changed from the point 213 to apoint 214 in the acousto-optic modulation unit 110 by second elasticwaves A_(V). Since wave vectors that the light L may have in thephotonic crystal structure of the acousto-optic modulation unit 110 arelimited by the equifrequency contour 207, a wave vector having a tip atthe point 214 may not exist in the wavenumber space shown in FIG. 5.Thus, the wave vector exits upward from the plane of the wavenumberspace shown in FIG. 5.

In FIGS. 5 and 6, reference numeral 209 denotes a window that may beconsidered an exit window through which light exits upward from theacousto-optic modulation unit 110. Reference numeral 205 denotes anequifrequency contour of wave vectors that the light L may have in air.That is, the tip of the wave vector of the light L in air is at a pointof the equifrequency contour 205. That is, the wave vector having a tipat the point 214 in FIG. 5 may be considered as a projection of a wavevector k_(light) having a tip at a point 215 in FIG. 6. In other words,the point 214 in the wavenumber space indicates light L propagating in aparticular direction in a 3-dimensional space.

Since the point 214 in the wavenumber space may be determined by designfactors such as the direction of light L incident on the acousto-opticmodulation unit 110, the intensities and directions of first and secondelastic waves A_(H) and A_(V), and the refractive index of theacousto-optic modulation unit 110, the direction of light L output fromthe acousto-optic element 100 may be adjusted by varying such designfactors.

For example, if the direction of light L incident on the acousto-opticmodulation unit 110, the directions of first and second elastic wavesA_(H) and A_(V), and the refractive index of the acousto-opticmodulation unit 110 are regulated by design specifications, thefrequencies of the first and second elastic waves A_(H) and A_(V) may bevaried and the amplitudes and phases of the first and second elasticwaves A_(H) and A_(V) may be varied according to the frequenciesthereof, so as to adjust the direction of light L exiting upward fromthe acousto-optic modulation unit 110. The direction of light L exitingupward from the acousto-optic modulation unit 110 may be expressed by azenith angle α and an azimuthal angle β. The frequencies and theamplitudes and phases by frequency of the first and second elastic wavesA_(H) and A_(V) may be determined by the frequencies and the amplitudesand phases by frequency of first and second high-frequency powersapplied to the first and second sound-wave generators 151 and 171.Therefore, the direction of light L output from the acousto-opticelement 100 may be adjusted by varying first and second high-frequencypowers to the first and second sound-wave generators 151 and 171. Inother words, light L output from the acousto-optic element 100 may beused for horizontal scanning by adjusting the frequency and theamplitude and phase by frequency of first high-frequency power, andlight L output form the acousto-optic element 100 may be used forvertical scanning by adjusting the frequency and the amplitude and phaseby frequency of second high-frequency power. That is, the first andsecond high-frequency waveguides 155 and 175 may be considered ashorizontal and vertical scanning lines of an optical scanner or displaypanel.

The above-described acousto-optic element 100 may be used in variousfields. For example, the acousto-optic element 100 may be used in a2-dimensional scanner for scanning with light L in horizontal andvertical directions. As described above, since the acousto-opticmodulation unit 110 has the photonic crystal structure, a largediffraction angle may be obtained for increasing the operational range(scanning range) of an optical scanner. Thus, the structures of opticalsystems used in the optical scanner may be simplified. In particular, anadditional optical system may not be used for increasing the range of adiffraction angle.

As described above, deflection by the acousto-optic effect may beunderstood as diffraction of light L in an acousto-optic medium whoselocal density is repeatedly varied by elastic waves. That is, theintensity of zeroth order diffraction light may be adjusted based on theamount of diffraction varying according to the frequency andintensity-by-frequency of elastic waves. Thus, the acousto-optic element100 of the current embodiment may be used as an optical modulator forzeroth order diffraction light. In addition, when light L is diffractedusing the acousto-optic element 100 by applying elastic waves, sinceother diffraction light components such as +1st or −1st orderdiffraction light are generated, zeroth order diffraction light passingthrough the acousto-optic element 100 may be weakened. In addition, ifother diffraction light components such as first order diffraction lighthave more energy according to diffraction conditions, zeroth orderdiffraction light may be further weakened. Therefore, the acousto-opticelement 100 may function as an optical modulator capable of amplitudemodulation. Further, the phase of light L may also be controlled byadjusting the propagation path or diffraction amount of the light L inthe acousto-optic element 100 so as to use the acousto-optic element 100as an optical modulator capable of phase modulation. In addition, theshape (wave pattern) of light L output from the acousto-optic element100 may also be controlled by adjusting the frequency and the intensityand phase by frequency of elastic waves.

In the current embodiment, the core layer 111 has a refractive indexgreater than those of the first and second cladding layers 112 and 113.However, this is a non-limiting example. For example, the relationshipamong the refractive indexes of the core layer 111 and the first andsecond cladding layers 112 and 113 may be relaxed as long as therefractive index of the core layer 111 is different from those of thefirst and second cladding layers 112 and 113, for the case in which thereflection layer 115 is disposed on the lower side of the first claddinglayer 112, the case in which some of the core layer 111 and the firstand second cladding layers 112 and 113 have photonic crystal structuresor meta-material structures, and other cases.

In the above-described embodiment, the acousto-optic element 100 has aphotonic crystal structure for increasing the acousto-optic effect.However, the embodiments are not limited thereto. For example, the corelayer 111 or the first and second cladding layers 112 and 113 of theacousto-optic modulation unit 110 may be formed of a meta materialhaving a plasmonic structure formed by a conductive material and adielectric material. Meta materials are materials having refractioncharacteristics that are not found in nature. In other words, metalmaterials are artificial atomic units including various patterns havingsubwavelength sizes. It is known that meta materials result in newphenomena such as subwavelength focusing, negative refraction,extraordinary transmission, and invisible cloaking for electromagneticwaves, sound waves, or ultrasonic waves. The above-mentioned photoniccrystals and plasmonic structure may be understood as examples of metalmaterials. If large diffraction is not necessary, such structures forincreasing the acousto-optic effect may not be used.

In FIG. 2, the second sound-wave generator 171 of the second sound-wavemodulation unit 170 is disposed in the reflection layer 115. However,the second sound-wave generator 171 of the second sound-wave modulationunit 170 may be disposed in the core layer 111, the first cladding layer112, or the second cladding layer 113. Similarly, the first sound-wavegenerator 151 of the first sound-wave modulation unit 150 may bedisposed in one of the core layer 111, the first cladding layer 112, thesecond cladding layer 113, and the reflection layer 115. In anotherexample, the first and second sound-wave generators 151 and 171 of thefirst and second sound-wave modulation units 150 and 170 may be disposedon interfaces among the core layer 111, the first cladding layer 112,the second cladding layer 113, the reflection layer 115, and thesubstrate 117. In addition, the first and second sound-wave generators151 and 171 of the first and second sound-wave modulation units 150 and170 may be disposed in different layers or the same layer.

In the above-described embodiment, the first and second sound-wavemodulation units 150 and 170 are disposed at the second and third sides110 b and 110 c of the acousto-optic modulation unit 110 to generatesound waves. However, the embodiments are not limited thereto. Forexample, at least two of the core layer 111, the first cladding layer112, the second cladding layer 113, the reflection layer 115, and thesubstrate 117 may be formed of piezoelectric materials (such as ZnO,PZT, LiNbO₃, LiTaO₃, quartz, and SrTiO₃), and may function as the firstand second sound-wave modulation units 150 and 170. For example, if thefirst cladding layer 112 is formed of a piezoelectric material, avoltage may be applied to the first cladding layer 112 to vibrate thefirst cladding layer 112. Thus, elastic waves are generated by thevibration of the first cladding layer 112. Since the direction ofelastic waves is determined by the arrangement of electrodes which applya voltage to a piezoelectric material or the crystalline direction ofthe piezoelectric material, the piezoelectric material may generateelastic waves in the second direction (negative (−) H-axis direction) orthe third direction (negative (−) V-axis direction). In an exemplaryconfiguration, one of the core layer 111, the first cladding layer 112,the second cladding layer 113, the reflection layer 115, and thesubstrate 117 may be formed of a piezoelectric material to function asthe first sound-wave modulation unit 150, and a separate sound-wavegenerator disposed at a side of the acousto-optic modulation unit 110may function as the second sound-wave modulation unit 170. In anotherexample, a configuration opposite to the exemplary configuration may beused.

Furthermore, in the above-described embodiment, it seems that theacousto-optic modulation unit 110 is spatially separated from the lightsupply unit 130 and the first and second sound-wave modulation units 150and 170. However, some layers of the acousto-optic modulation unit 110(such as the core layer 111 or the first cladding layer 112) may extendoutward from the region of the acousto-optic modulation unit 110. Inthis case, the acousto-optic modulation unit 110 may be considered as aregion surrounded by the light supply unit 130 and the first and secondsound-wave modulation units 150 and 170. Furthermore, in theabove-described embodiment, the photonic crystal structure may beconsidered to be formed in a region of the acousto-optic modulation unit110 surrounded by the light supply unit 130 and the first and secondsound-wave modulation units 150 and 170.

In the above-described embodiment, a grating coupler is described as theoptical coupler 135. However, any other optical coupling device known inthe art may be used as the optical coupler 135. For example, a lens orprism may be disposed between the optical waveguide 131 and the corelayer 111. In another example, the optical waveguide 131 of the lightsupply unit 130 and the core layer 111 may be in contact with each otherwithout using the optical coupler 135. In another example, the opticalcoupler 135 may be formed by arranging semi-transparent reflectionlayers at an oblique angle in the optical waveguide 131 disposed on theexposed top region of the core layer 111.

Further more, in the above-described embodiment, the light supply unit130 is constituted by the optical waveguide 131 and the optical coupler135. However, the embodiments are not limited thereto. For example, thelight supply unit 130 may be a light source disposed at the first side110 a of the acousto-optic modulation unit 110.

In the above-described embodiment, the arrangement of the light supplyunit 130, the first sound-wave modulation unit 150, and the secondsound-wave modulation unit 170 is exemplary. That is, the embodimentsare not limited thereto. As long as the first direction in which light Lis incident on the acousto-optic modulation unit 110, the seconddirection in which first elastic waves A_(H) are generated by the firstsound-wave modulation unit 150, and the third direction in which secondelastic waves A_(V) are generated by the second sound-wave modulationunit 170 are different, the light L incident on the acousto-opticmodulation unit 110 may be deflected toward the window 209 (refer toFIG. 5) by adjusting the amplitudes and phases of the first and secondelastic waves A_(H) and A_(V) so that the light L may exit from theacousto-optic modulation unit 110 through the window 209.

FIG. 7 is a schematic plan view illustrating an acousto-optic elementarray 200 according to according to an embodiment, and FIG. 8 is a viewillustrating an exemplary arrangement of a light supply unit 130 andfirst and second sound-wave modulation units 150 and 170 in theacousto-optic element array 200.

Referring to FIGS. 7 and 8, the acousto-optic element array 200 of theembodiment includes acousto-optic modulation units 110 2-dimensionallyarranged on a substrate 210, a light supply unit 130 configured tosupply light to the acousto-optic modulation units 110, a firstsound-wave modulation unit 150 configured to generate first elasticwaves A_(H) toward the acousto-optic modulation units 110, and secondsound-wave modulation units 170 configured to generate second elasticwaves A_(V) toward the acousto-optic modulation units 110. The substrate210 may have a flat or curved surface.

The acousto-optic modulation units 110 are arranged in a plurality ofcolumns and a plurality of rows. The 2-dimensional arrangement of theacousto-optic modulation units 110 may be understood as a matrixarrangement of pixels in a display panel. A core layers 111 (refer toFIG. 2) and a first cladding layer 112 (refer to FIG. 2) of theacousto-optic modulation units 110 may extend outward from theacousto-optic modulation units 110 and cover the entire region of thesubstrate 210. The acousto-optic modulation units 110 may be within aninner region surrounded by the light supply unit 130 and the first andsecond sound-wave modulation units 150 and 170, and photonic crystalstructures may only be formed in the inner region.

The light supply unit 130 extends along an outer side of one of theoutermost columns of the arrangement of the acousto-optic modulationunits 110. In detail, a optical waveguide 131 (refer to FIG. 1) of thelight supply unit 130 extends along the outer side of one of theoutermost columns of the arrangement of the acousto-optic modulationunits 110, and optical couplers 135 (refer to FIG. 1) are disposedbetween the optical waveguide 131 and the acousto-optic modulation units110 to direct light from the optical waveguide 131 to the acousto-opticmodulation units 110.

The first sound-wave modulation unit 150 may extend along an outer sideof one of the outermost rows of the arrangement of the acousto-opticmodulation units 110. As shown in FIG. 8, a first sound absorbing member159 may also extend along the outer side of one of the outermost rows ofthe arrangement of the acousto-optic modulation units 110.

The second sound-wave modulation units 170 may be individually disposedon sides of the acousto-optic modulation units 110. As shown in FIG. 8,second sound absorbing members 179 may also be individually disposedtogether with the second sound-wave modulation units 170.

As described above, the acousto-optic modulation units 110, the lightsupply unit 130, and the first and second sound-wave modulation units150 and 170 may be disposed on the flat substrate 210 so that theacousto-optic element array 200 may be used as a flat panel.

Next, an exemplary operation of the acousto-optic element array 200 willbe described.

Referring to FIG. 7, the light supply unit 130 may simultaneously supplylight to the one of the outermost columns of the acousto-opticmodulation units 110 in a first direction (a positive (+) V-axisdirection or a direction making an acute angle therewith). In addition,as described above, since the core layer 111 and the first claddinglayer 112 of the acousto-optic modulation units 110 extend outward fromthe acousto-optic modulation units 110 and cover the entire region ofthe substrate 210, the light incident on the one of the outermost columnof the acousto-optic modulation units 110 may propagate all over thesubstrate 210 through the core layer 111. That is, the light supply unit130 may be commonly used for the acousto-optic modulation units 110.

Similarly, the first sound-wave modulation unit 150 may simultaneouslyapply first elastic waves to the one of the outermost rows of theacousto-optic modulation units 110 in a second direction (for example, anegative (−) H-axis direction). No sound absorbing member is disposedbetween the first sound-wave modulation unit 150 and the acousto-opticmodulation units 110 in the second direction. Thus, the first elasticwaves may propagate through the acousto-optic modulation units 110 inthe second direction. That is, the first sound-wave modulation unit 150may also be commonly used for the acousto-optic modulation units 110.

Since the second sound-wave modulation units 170 are respectivelyprovided for the acousto-optic modulation units 110, the secondsound-wave modulation units 170 individually apply second elastic wavesto the acousto-optic modulation units 110. Since the second soundabsorbing members 179 are individually provided for the acousto-opticmodulation units 110 together with the second sound-wave modulationunits 170, noises caused by second elastic waves of neighboringacousto-optic modulation units 110 may be removed by the second soundabsorbing members 179.

In the acousto-optic element array 200, all the acousto-optic modulationunits 110 share the light supply unit 130 and the first sound-wavemodulation unit 150, and the direction of light L output from theacousto-optic modulation units 110 may be adjusted by varying secondelastic waves generated by the second sound-wave modulation units 170.In other words, horizontal scanning may be performed by commonly usingthe acousto-optic modulation units 110 (i.e., pixels), and verticalscanning may be performed by individually using the acousto-opticmodulation units 110 (i.e., pixels).

As described above, light L incident on the acousto-optic modulationunits 110 may be diffracted by first and second elastic waves generatedby the first and second sound-wave modulation units 150 and 170 and maybe output upward, and the direction and shape of the output light L maybe controlled by varying the frequencies and the amplitudes and phasesby frequency of the first and second elastic waves. Therefore, theacousto-optic element array 200 of the current embodiment may functionas a multi-directional surface light source capable of emitting light Ltoward a plurality of visual fields.

In addition, according to the current embodiment, the intensity of lightL output from the acousto-optic element array 200 may be adjusted byvarying the amplitudes and phases of first and second elastic waves.Thus, the acousto-optic element array 200 may function as a2-dimensional display panel. Furthermore, according to the currentembodiment, the intensity and direction of light L output from theacousto-optic element array 200 may be simultaneously adjusted byvarying the frequencies and the amplitudes and phases by frequency offirst and second elastic waves. Thus, the acousto-optic element array200 may function as a multi-directional, 3-dimensional display panelcapable of providing multiple viewpoints. Furthermore, since theacousto-optic element array 200 of the current embodiment may functionas an optical modulator capable of phase modulation, the acousto-opticelement array 200 may be used as a hologram panel capable of providingholographic images by supplying computer generated holograms (CGHs) tothe first and second sound-wave modulation units 150 and 170 as electricsignals. Furthermore, the acousto-optic element array 200 of the currentembodiment may provide optical controlling for optical interconnection.

The arrangement of the light supply unit 130, the first and secondsound-wave modulation units 150 and 170 shown in the current embodimentis an exemplary one. Various other arrangements may be used. FIGS. 9A to9A are views illustrating exemplary arrangements of light supply units130 and first and second sound-wave modulation units 150 and 170 thatmay be applied to the acousto-optic element array 200 of FIG. 7.

For example, referring to FIG. 9A, light supply units 130 may extendalong sides of a plurality of columns of arrayed acousto-opticmodulation units 110, and first and second sound-wave modulation units150 and 170 may be individually provided for the respectiveacousto-optic modulation units 110.

In another example shown in FIG. 9B, light supply units 130 may extendalong sides of a plurality of columns of arrayed acousto-opticmodulation units 110, first sound-wave modulation units 150 may beindividually provided at rear ends of columns of the acousto-opticmodulation units 110, and second sound-wave modulation units 170 may beprovided for the respective acousto-optic modulation units 110. In thiscase, the light supply units 130 may be commonly used for all theacousto-optic modulation units 110, and the first sound-wave modulationunits 150 may be commonly used for the columns of the acousto-opticmodulation units 110, respectively.

In another example shown in FIG. 9C, light supply units 130 may extendalong sides of a plurality of columns of arrayed acousto-opticmodulation units 110, a first sound-wave modulation unit 150 may extendalong an outer side of one of the outermost rows of the arrayedacousto-optic modulation units 110, and second sound-wave modulationunits 170 may be provided for the acousto-optic modulation units 110,respectively. In this case, the light supply units 130 and the firstsound-wave modulation unit 150 may be commonly used for all theacousto-optic modulation units 110.

In another example shown in FIG. 9D, a light supply unit 130 may extendalong an outer side of one of the outermost columns of arrayedacousto-optic modulation units 110, first sound-wave modulation units150 may be individually provided at rear ends of columns of theacousto-optic modulation units 110, and second sound-wave modulationunits 170 may be provided for the acousto-optic modulation units 110,respectively.

In another example shown in FIG. 9E, light supply units 130 and secondsound-wave modulation units 170 may extend along both sides of aplurality of columns of arrayed acousto-optic modulation units 110, andfirst sound-wave modulation units 150 may be individually provided forthe acousto-optic modulation units 110, respectively.

In another example shown in FIG. 9F, a light supply unit 130 may extendalong an outer side of one of the outermost columns of arrayedacousto-optic modulation units 110, first sound-wave modulation units150 may be individually provided for the acousto-optic modulation units110, respectively, and second sound-wave modulation units 170 may extendalong sides of the plurality of columns of the acousto-optic modulationunits 110.

In another example shown in FIG. 9G, light supply units 130 may extendalong sides of a plurality of columns of arrayed acousto-opticmodulation units 110, first sound-wave modulation units 150 may beindividually provided for the acousto-optic modulation units 110,respectively, and a second sound-wave modulation unit 170 may extendalong an outer side of one of the outermost columns of the acousto-opticmodulation units 110.

In another example shown in FIG. 9H, a light supply unit 130 may extendalong an outer side of one of the outermost columns of arrayedacousto-optic modulation units 110, a second sound-wave modulation units170 may extend along an outer side of the other of the outermost columnsof the acousto-optic modulation units 110, and first sound-wavemodulation units 150 may be individually provided for the acousto-opticmodulation units 110, respectively.

The arrangements of the light supply units 130 and the first and secondsound-wave modulation units 150 and 170 shown in FIGS. 9A to 9H areexamples for forming acousto-optic electrode arrays. That is, it will beapparent to those of ordinary skill in the art that various combinationsand modifications may be made therefrom. For example, an arrangement inwhich first sound-wave modulation units 150 extend along sides of aplurality of rows of arrayed acousto-optic modulation units 110 may beapplied to the above-described arrangements.

FIGS. 10A to 10C are views illustrating exemplary arrangements of lightsupply units 130 and first and second sound-wave modulation units 150and 170 in acousto-optic element arrays according to other embodiments.

In the acousto-optic element arrays shown in FIGS. 10A to 10C,acousto-optic modulation units 110 are arranged in a line. In suchone-dimensional acousto-optic element arrays, arrangements of lightsupply units 130 and first and second sound-wave modulation units 150and 170 may be variously combined as shown in FIGS. 10A to 10C.

For example, referring to FIG. 10A, a light supply units 130 may extendalong an outer side of a column of acousto-optic modulation units 110,and first and second sound-wave modulation units 150 and 170 may beindividually provided for the respective acousto-optic modulation units110. In another example shown in FIG. 10B, a light supply units 130 mayextend along an outer side of a column of acousto-optic modulation units110, a first sound-wave modulation unit 150 may be disposed at a rearend of the column of the acousto-optic modulation units 110, and secondsound-wave modulation units 170 may be individually provided for theacousto-optic modulation units 110, respectively. In another exampleshown in FIG. 10C, a light supply units 130 and a second sound-wavemodulation unit 170 may extend along both outer sides of a column ofacousto-optic modulation units 110, and first sound-wave modulationunits 150 may be individually provided for the acousto-optic modulationunits 110, respectively. The arrangements of the light supply units 130and the first and second sound-wave modulation units 150 and 170 shownin FIGS. 10A to 10C are examples for forming acousto-optic electrodearrays. That is, one of ordinary skill in the art would understand thatvarious combinations and modifications may be made therefrom.

FIG. 11 is a schematic view illustrating a display apparatus 300including an acousto-optic element array according to an embodiment.

The display apparatus 300 includes an acousto-optic element array suchas those described in the previous embodiments. For example, the displayapparatus 300 may include the acousto-optic element array 200 of theprevious embodiment (refer to FIG. 7) as a pixel array of a displaypanel 310.

Since the intensity and direction of light L output from theacousto-optic element array 200 are adjusted by varying the frequenciesand the amplitudes and phases by frequency of first and second elasticwaves, the acousto-optic element array 200 may be used as amulti-directional, 3-dimensional display panel capable of providingmultiple viewpoints. In addition, only the intensity of light L outputfrom the acousto-optic element array 200 may be selectively adjusted.Therefore, the display apparatus 300 using the acousto-optic elementarray 200 in the display panel 310 may function as a 2D/3D convertible3-dimensional display apparatus.

Furthermore, since the acousto-optic element array 200 may function asan optical modulator capable of phase modulation, the display apparatus300 using the acousto-optic element array 200 in the display panel 310may function as a holographic display apparatus by supplying computergenerated holograms (CGHs) to the first and second sound-wave modulationunits 150 and 170 as electric signals.

In addition, since the acousto-optic element array 200 may be flat, thedisplay panel 310 using the acousto-optic element array 200 may be aflat display panel, and the display apparatus 300 may also be a flatdisplay apparatus.

It should be understood that the exemplary embodiments described thereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While the acousto-optic element, the acousto-optic element array, andthe display apparatus including the acousto-optic element have beendescribed according to the embodiments with reference to the figures, itwill be understood by those of ordinary skill in the art that variouschanges in form and details may be made therein without departing fromthe spirit and scope of the embodiments as defined by the followingclaims.

What is claimed is:
 1. An acousto-optic element array comprising aplurality of acousto-optic elements, wherein each of the plurality ofacousto-optic elements comprises: an acousto-optic modulator whichcomprises an acousto-optic layer formed of an acousto-optic material; alight supplier which supplies light to the acousto-optic modulator in afirst direction; a first sound-wave modulator which applies firstelastic waves to the acousto-optic modulator in a second direction; anda second sound-wave modulator which applies second elastic waves to theacousto-optic modulator in a third direction, wherein the light suppliedfrom the light supplier to the acousto-optic modulator is deflected bydiffraction caused by the first elastic waves applied from the firstsound-wave modulator and diffraction caused by the second elastic wavesapplied from the second sound-wave modulator, and is output from theacousto-optic modulator through a front side of the acousto-opticmodulator, wherein a plurality of acousto-optic modulators correspondingto each of the plurality of acousto-optic elements are arranged in atleast one line.
 2. The acousto-optic element array of claim 1, whereinthe acousto-optic modulators are arranged in a single line.
 3. Theacousto-optic element array of claim 2, wherein the light supplier, thefirst sound-wave modulator, and the second sound-wave modulator of eachof the plurality of acousto-optic elements are disposed at differentpositions of a front end, a rear end, a side, and an other side of thesingle line of the acousto-optic modulators.
 4. The acousto-opticelement array of claim 3, wherein one of the light supplier, the firstsound-wave modulator, and the second sound-wave modulator which isdisposed at the side or the other side of the single line of theacousto-optic modulators is formed to extend along the single line andis commonly used for the acousto-optic modulators.
 5. The acousto-opticelement array of claim 3, wherein one of the light supplier, the firstsound-wave modulator, and the second sound-wave modulator which isdisposed at the side or the other side of the line of the acousto-opticmodulators is individually provided for each of the acousto-opticmodulators.
 6. The acousto-optic element array of claim 3, wherein oneof the light supplier, the first sound-wave modulator, and the secondsound-wave modulator which is disposed at the front end or the rear endof the line of the acousto-optic modulators is commonly used for theacousto-optic modulators.
 7. The acousto-optic element array of claim 1,wherein the acousto-optic modulators are arranged in a plurality ofcolumns and a plurality of rows.
 8. The acousto-optic element array ofclaim 7, wherein the light supplier of the plurality of acousto-opticelements extends along an outer side of one of outermost columns of theacousto-optic modulators.
 9. The acousto-optic element array of claim 7,wherein the light supplier of the plurality of acousto-optic elementsextends along sides of the respective columns of the acousto-opticmodulators.
 10. The acousto-optic element array of claim 7, wherein thefirst sound-wave modulator of the plurality of acousto-optic elementsextends along an outer side of one of outermost rows of theacousto-optic modulators.
 11. The acousto-optic element array of claim7, wherein a plurality of first sound-wave modulators of the pluralityof acousto-optic elements are arranged along an outer side of one ofoutermost rows of the acousto-optic modulators, so as to be respectivelydisposed at the columns of the acousto-optic modulators.
 12. Theacousto-optic element array of claim 7, wherein a plurality of firstsound-wave modulators of the plurality of acousto-optic elements areformed to extend along sides of the respective rows of the acousto-opticmodulators.
 13. The acousto-optic element array of claim 7, wherein aplurality of first sound-wave modulators of the plurality ofacousto-optic elements are individually arranged at sides of therespective rows of the acousto-optic modulators.
 14. The acousto-opticelement array of claim 8, wherein the second sound-wave modulator of theplurality of acousto-optic elements extends along the outer side of another of the outermost columns of the acousto-optic modulators.
 15. Theacousto-optic element array of claim 8, wherein a plurality of secondsound-wave modulators of the plurality of acousto-optic elements arearranged along the outer side of an other of the outermost columns ofthe acousto-optic modulators, so as to be respectively disposed at therows of the acousto-optic modulators.
 16. The acousto-optic elementarray of claim 7, wherein a plurality of second sound-wave modulators ofthe plurality of acousto-optic elements are formed to extend along sidesof the respective columns of the acousto-optic modulators.
 17. Theacousto-optic element array of claim 7, wherein a plurality of secondsound-wave modulators of the plurality of acousto-optic elements areindividually arranged at sides of the respective columns of theacousto-optic modulators.
 18. A display apparatus comprising a displaypanel comprising an acousto-optic element array, the acousto-opticelement array comprising a plurality of acousto-optic elements, whereineach of the plurality of acousto-optic elements comprises: anacousto-optic modulator which comprises an acousto-optic layer formed ofan acousto-optic material; a light supplier which supplies light to theacousto-optic modulator in a first direction; a first sound-wavemodulator which applies first elastic waves to the acousto-opticmodulator in a second direction; and a second sound-wave modulator whichapplies second elastic waves to the acousto-optic modulator in a thirddirection, wherein the light supplied from the light supplier to theacousto-optic modulator is deflected by diffraction caused by the firstelastic waves applied from the first sound-wave modulator anddiffraction caused by the second elastic waves applied from the secondsound-wave modulator, and is output from the acousto-optic modulatorthrough a front side of the acousto-optic modulator, wherein theacousto-optic modulators of the plurality of acousto-optic elements arearranged in at least one line, wherein a plurality of images aredisplayed by controlling at least one of directions, phases, andintensities of the light output from front sides of the acousto-opticmodulators 2-dimensionally arranged in the display panel.
 19. Thedisplay apparatus of claim 18, wherein the display apparatus displays2-dimensional images having a single viewpoint regardless of thedirections of the light output from the display panel.
 20. The displayapparatus of claim 18, wherein the display panel adjusts viewpoint dataof the images according to the directions of the light output from thedisplay panel so as to form at least two visual fields for displaying3-dimensional images.
 21. The display apparatus of claim 18, whereinswitching between 2-dimensional images and 3-dimensional images isperformed by selectively adjusting image data according to thedirections of the light output from the display panel.
 22. The displayapparatus of claim 20, wherein the at least two visual fields are formedin at least one of a horizontal direction and a vertical direction. 23.The display apparatus of claim 18, wherein a plurality of hologramimages are displayed by adjusting the intensities and the phases of thelight output from the display panel according to the directions of thelight.